implement --module (#5462)

lib/compress.js

@@ -80,6 +80,7 @@ function Compressor(options, false_by_default) {
         keep_infinity   : false,
         loops           : !false_by_default,
         merge_vars      : !false_by_default,
+        module          : false,
         negate_iife     : !false_by_default,
         objects         : !false_by_default,
         optional_chains : !false_by_default,
@@ -97,7 +98,7 @@ function Compressor(options, false_by_default) {
         switches        : !false_by_default,
         templates       : !false_by_default,
         top_retain      : null,
-        toplevel        : !!(options && options["top_retain"]),
+        toplevel        : !!(options && (options["module"] || options["top_retain"])),
         typeofs         : !false_by_default,
         unsafe          : false,
         unsafe_comps    : false,
@@ -130,6 +131,7 @@ function Compressor(options, false_by_default) {
         var escaped = def.escaped;
         return escaped && escaped.depth != 1;
     };
+    if (this.options["module"]) this.directives["use strict"] = true;
     var pure_funcs = this.options["pure_funcs"];
     if (typeof pure_funcs == "function") {
         this.pure_funcs = pure_funcs;
@@ -7360,6 +7362,7 @@ Compressor.prototype.compress = function(node) {
             }
         });
         tt.push(compressor.parent());
+        tt.directives = Object.create(compressor.directives);
         self.transform(tt);
         if (self instanceof AST_Lambda
             && self.body.length == 1

lib/minify.js

@@ -81,13 +81,14 @@ function minify(files, options) {
             keep_fargs: false,
             keep_fnames: false,
             mangle: {},
+            module: false,
             nameCache: null,
             output: {},
             parse: {},
             rename: undefined,
             sourceMap: false,
             timings: false,
-            toplevel: false,
+            toplevel: !!(options && options["module"]),
             v8: false,
             validate: false,
             warnings: false,
@@ -101,6 +102,7 @@ function minify(files, options) {
         if (options.ie) set_shorthand("ie", options, [ "compress", "mangle", "output", "rename" ]);
         if (options.keep_fargs) set_shorthand("keep_fargs", options, [ "compress", "mangle", "rename" ]);
         if (options.keep_fnames) set_shorthand("keep_fnames", options, [ "compress", "mangle", "rename" ]);
+        if (options.module) set_shorthand("module", options, [ "compress", "parse" ]);
         if (options.toplevel) set_shorthand("toplevel", options, [ "compress", "mangle", "rename" ]);
         if (options.v8) set_shorthand("v8", options, [ "mangle", "output", "rename" ]);
         if (options.webkit) set_shorthand("webkit", options, [ "compress", "mangle", "output", "rename" ]);

lib/parse.js

@@ -237,8 +237,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         newline_before  : false,
         regex_allowed   : false,
         comments_before : [],
-        directives      : {},
-        directive_stack : [],
+        directives      : Object.create(null),
         read_template   : with_eof_error("Unterminated template literal", function(strings) {
             var s = "";
             for (;;) {
@@ -635,23 +634,19 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
     };
 
     next_token.add_directive = function(directive) {
-        S.directive_stack[S.directive_stack.length - 1].push(directive);
-        S.directives[directive] = (S.directives[directive] || 0) + 1;
+        S.directives[directive] = true;
     }
 
     next_token.push_directives_stack = function() {
-        S.directive_stack.push([]);
+        S.directives = Object.create(S.directives);
     }
 
     next_token.pop_directives_stack = function() {
-        var directives = S.directive_stack.pop();
-        for (var i = directives.length; --i >= 0;) {
-            S.directives[directives[i]]--;
-        }
+        S.directives = Object.getPrototypeOf(S.directives);
     }
 
     next_token.has_directive = function(directive) {
-        return S.directives[directive] > 0;
+        return !!S.directives[directive];
     }
 
     return next_token;
@@ -698,6 +693,7 @@ function parse($TEXT, options) {
         expression     : false,
         filename       : null,
         html5_comments : true,
+        module         : false,
         shebang        : true,
         strict         : false,
         toplevel       : null,
@@ -2545,6 +2541,7 @@ function parse($TEXT, options) {
     return function() {
         var start = S.token;
         var body = [];
+        if (options.module) S.input.add_directive("use strict");
         S.input.push_directives_stack();
         while (!is("eof"))
             body.push(statement());